The new research suggests that opioid painkillers in fact increase the severity and duration of chronic pain. Examples of the painkillers include morphine, oxycodone and methadone.

The study looked at the effects of drugs in animal model. Here researchers studied the effects of morphine on rats. The examination found that, with a short course of treatment, administered after nerve injury, considerably increased the length of time that pain was experienced for.

The study found the administration of opioids doubled the duration of neuropathic pain. This was because the medication exacerbated the release of pain signals from glial cells in the spinal cord. While animal models do not always match human experiences, there is something concerning about the findings.

In a statement, the lead researcher Professor Peter Grace said: “We are showing for the first time that even a brief exposure to opioids can have long-term negative effects on pain.” Essentially the scientist says he found “found the treatment was contributing to the problem.”

Opioids are not only a concern in terms of how effective they are in managing pain, the drugs are increasingly associated with misuse. Here the U.S. Centers for Disease Control and Prevention (CDC) and National Center for Health Statistics (NCHS) have jointly published data about the rise in opioid-related overdoses. In 2014, some 19,000 U.S. citizens died as a result of opioid overdoses. Whereas, in 2004, the death rate was lower, at 4,000 deaths.

Putting this together in an overall analysis, Kent Runyon of Novus Medical Detox Center, says the case needs to be made for using alternative, non-opioid based pain management treatment options. One example of an alternative treatment are Designer Receptor Exclusively Activated by Designer Drugs (DREADD.) Here Runyon says: “opioids should not be first-line or routine therapy for chronic pain.”

More could be done, however. Runyon argues: “Ideally, I’d like to see the industry invest in further research to identify an alternative solution—one that provides equally effective pain relief, does not exacerbate or prolong pain, is not harmful to the patient and minimizes the risk of addiction and overdoses.”

The study has been carried out at the University of Colorado Boulder. The paper is published in the Proceedings of the National Academy of Sciences and it is titled “Morphine Paradoxically Prolongs Neuropathic Pain in Rats by Amplifying Spinal NLRP3 Inflammasome Activation.”